The present invention relates to a parallel imaging method and an MRI (Magnetic Resonance Imaging) apparatus. More particularly, the invention relates to a parallel imaging method and an MRI apparatus capable of obtaining a composite image by unfolding operation with a small computation amount and short process time by using three or more reception coils.
Hitherto, a parallel imaging method is known in which a scan with reduced number of phase encoding steps is performed by using a plurality of reception coils, data of the reception coils is collected, images are generated from the data, and a composite image is obtained by unfolding a folded image by unfolding operation using the difference of sensitivity distributions of the reception coils (refer to, for example, Patent Document 1 and Non-Patent Document 1).
[Patent Document 1] Japanese Unexamined Patent Publication No. 2003-79595
[Non-Patent Document 1] Klaas P. Pruessmann et al. “SENSE: Sensitivity Encoding for Fast MRI”, Magnetic Resonance in Medicine 42 (1999), pp. 952-962
The conventional unfolding operation has a problem such that when the number of reception coils becomes N (≧3), the computation amount increases by the number of possible combinations of two values in N as compared with that in the case where the number of reception coils is 2, and the computation amount sharply increases. For example, when the number of reception coils is three, the computation amount increases by three times. When the number of reception coils is four, the computation amount increases by six times.